This invention generally relates to power closure systems for vehicles. More particularly, this invention relates to obtaining initialization information for controlling movement of the position of a vehicle panel that can be automatically closed by a power closure system.
Power closure systems are used on vehicles for power sliding doors and power lift gates, for example. Typical arrangements have a clutch to selectively establish a mechanical coupling between an actuator such as a motor and the door or lift gate. The motor control arrangement typically includes a position sensor that monitors the position of the door during a power closure. Typical arrangements include “relative” position sensors such as encoders or Hall effect sensors associated with a rotating armature. Such relative sensors cannot tell absolute position and, therefore, techniques must be employed to achieve accurate position information for use during a power closure. It is necessary to initialize the position information from the sensor when the actual door or lift gate position is known.
Conventional techniques include initializing the position when the door or lift gate is closed. In conventional arrangements, however, the clutch is disengaged when the door is closed and the closure system is not in a state that accurately represents an operating state. For example, wire play and gear backlash occur because the system is no longer under tension once the clutch is disengaged. After this, there is not a proper correlation between the sensor position and the door or lift gate position. Therefore, position initialization is not accurate or reliable with such an approach.
This invention provides improved position initialization, in part, by eliminating any slack in the coupling between the motor and the door or lift gate prior to determining the initialization position information.